PR16716 partial fix: Fix types and compat support in timer syscalls family

PR16716 partial fix: Fix types and compat support in timer syscalls family

* tapset/linux/syscalls2.stp:
  syscall.timer_{delete,getoverrun,gettime,settime}: Fix types
  syscall.timer_gettime: Add compat support
* tapset/linux/nd_syscalls2.stp (timer_gettime): Add compat support
* tapset/linux/aux_syscalls.stp: Print the pointer value
  when _stp_copy_from_user() fails instead of reporting "UNKNOWN"
* testsuite/systemtap.syscall/test.tcl: Link with -lrt to allow
  using glibc wrappers for timer syscalls family
* testsuite/systemtap.syscall/timer.c: Add more tests